The proposed three year project is to continue our investigation into the biochemical and physiological aspects of lung lactate metabolism. Examined in detail will be the role of lactate in lung lipid synthesis, lactate metabolism under altered physiologic states, regulatory mechanisms of lactate metabolism, and the role of lactate as a potential substrate for alveolar type II cell metabolism. To accomplish the overall objectives of this proposed investigation, the isolated perfused lung, cell separation and biochemical techniques will be used. Specific experiments will be designed to examine: 1) the effect of hypoxia, ischemia, and hyperoxia on lactate metabolism, 2) contributions of lactate to surface active lipid synthesis, 3) changes in LDH activity and LDH isozyme patterns during altered physiologic states, 4) rate limiting steps of glycolysis in the lung and 5) role of lactate in lung type II cell metabolism.